Processing tachydrite ore

ABSTRACT

A solution of tachydrite ore is employed in the recovery of useful components of soluble ores. In one embodiment a tachydrite-containing solution is added to a solution containing carnallite or sylvinite ore to precipitate carnallite or sylvinite, while in another embodiment, the tachydrite-containing solution is added to a solution of halite ore to precipitate sodium chloride values.

United States Patent 1191 Nylander Aug. 19, 1975 [54] PROCESSINGTACHYDRITE ORE 2.699.379 1 1955 Luque 423/499 ux 2,733,257 4/1957 Duke423/184 [761 memo Alfred Nylande." 3.498.745 3/1970 Nylander 423/184Ave., Redwood C1ty, Callf. 94064 [22] Filed: May 14, 1973 PrimaryExaminer-Edward Stern [211 App]. No.: 360.000

[57] ABSTRACT 52 us. (:1. 423/184; 423/197; 423/497; A Solution oftachydrite Ore is employed in recov- 423/499 ery of useful components ofsoluble ores. in one em- I] In. C. o 3 0 o 3 o t 5 0 bodiment atachydrite-containing Solution is added to [58] Field of Search H423/499 497 184 197 a solution containing carnallite or sylvinite ore toprecipitate camallite or sylvinite, while in another em [56] ReferencesCited bodiment, the tachydrite-comaining solution is added UNITED STATESPATENTS to a solution of halite ore to precipitate sodium chloridevalues. 1.252.784 1/1918 Cox 423/499 x 1.863.75l 6/[932 Kipper 423/184 6Claims, 2 Drawing Figures 2 4 2 4 V s fi 51 7 s2 54 V ss fi i 5 H l Hcnmuunc mg" 140111011115 snvmn: mama ncnvnmz out out ORE 55 mus ORE -s I,7 name 56 1111011511511 1 7 I an H 0 s2- rmcucnsa -57 2 r w 59 6| mm 1'l5 6l)\ 1s fl o mm '4 oscourosmou as mus l6 BEIIEFIGIATIOR Pommu 14,0122\ vnogucr 51am mclmn A n 1 n LITE BLEEIJ 65 9 PRDDUOI "20 l l 21FILTER 1 2a 0111511 raooucr w arm :53

PATEN itu i 5:: 1.1 N 05 3 LII 2 522: z 5555 a as; m5; I1 a uz fi szo 155 A 2223525 11 2 2 d 2;: a 3:228: 2 5:: ON: 2 3 e 5:: u GEM a 6 m: a s5535 s T $52.: Q :5 a :0 ea: 5 E as E53: .555 E 5:: E55: E355 A e m V Lo B [a m [n Q N 1 PROCESSING TACI-[YDRITE ORE DESCRIPTION OF THEINVENTION This invention relates to the mining and processing of oresand more particularly to the mining and processing of carnallite,sylvinite or halite ores in conjunction with the mining of tachydriteore.

In the mining of ores such as those containing potash values, it issometimes not economically feasible to dry mine the ore by sinking ashaft to the deposit. Shaft mining may be ruled out because of depth ofthe deposit, lack of stability of the geological formation surroundingthe ore body, lack of stability of the ore body itself, or a variety ofother factors. Solution mining is a possible alternative in someinstances but requires a minimum ore bed height and requires that thedissolved mineral be recovered from the solution. The economic burdenimposed by that recovery can be substantial and solution mining does notalways constitute an economically attractive alternative. This isparticularly true when the potash mineral is in a mixed bed with othersoluble but economically unattractive minerals. Carnallite ore, forexample, is generally regarded as an unattractice source of potassium.

The Sergipe potash deposit of Brazil and a similar deposit in the Congoof Africa are examples of potash and carnallite deposits that have notbeen utilized. The ore body is a complex combination of three principalconstituents in semi-distinct but closely related ore zones. One zonecontains sylvinite. a mixture of sylvite (KCl) and halite (NaCl),another zone contains primarily carnallite (KCI MgCl 6H O), and thethird zone consists largely of tachydrite (CaCl 2MgCl l2H-,O). Themake-up of the ore body, its depth, and the potential plastic flow ofcarnallite and tachydrite make it unlikely that shaft and drift miningof the sylvinite zone can be successful. Because of the nature of theore body and the expense of fossil fuels or the like needed forconventional mineral recovery, solution mining has not been attemptedeither. Although the Sergipe deposit long has been known to exist, andalthough it represents a large potash reserve, the ore body remainsunmined.

It is a broad object of this invention to employ a solution oftachydrite ore to recover desirable components from soluble mineralchloride ores.

It is a further object of this invention to employ a solution oftachydrite ore in the treatment of a solution of carnallite ore for therecovery of potassium values therefrom.

It is still a further object of this invention to employ a solution oftachydrite ore in the treatment of a solution of sylvinite ore for therecovery of potassium values therefrom.

It is another object of this invention to employ a solution oftachydrite ore in the treatment of a solution of a mixture of carnalliteand sylvinite ores for the recovery of potassium values therefrom.

It is an additional object of this invention to employ a solution oftachydrite ore in the treatment of a solution of halite-ore to obtainsodium chloride therefrom.

In accordance with one embodiment of this invention there is provided aprocess which comprises:

1. forming a saturated aqueous solution of tachydrite ore;

2. forming an aqueous solution containing carnallite, sylvinite ormixtures thereof, saturated with respect to potassium chloride;

3. mixing said solutions whereby potassium chloridecontaining solids areprecipitated; and

4. beneficiating said potassium chloride-containing solids to providepotassium chloride.

If carnallite is processed according to this invention the precipitatedsolids will contain potassium chloride and magnesium chloride; ifsylvinite is processed according to this invention the precipitatedsolids will contain potassium chloride and sodium chloride; and ifmixtures of carnallite and sylvinite are processed according to thisinvention the precipitated solids will contain potassium chloride,magnesium chloride and sodium chloride. As indicated below, any of thesemixtures may then be beneficiated by known techniques to providepotassium chloride values.

In accordance with another embodiment of this invention, there isprovided a process which comprises:

1. forming a saturated aqueous solution of tachydrite ore;

2. forming a saturated aqueous solution of halite; and

3. mixing said solutions whereby sodium chloride is precipitated.

This invention combines a solution of one unattractive ore with asolution of another ore generally regarded to be unattractive in orderto obtain an economically attractive product. The solutions may beformed by solution mining the ores and the ore solutions thereaftercombined to yield the desired product. Although calciumchloride-containing ore bodies such as tachy drite are not economicallyattractive, the use of tachydrite permits, for example, solution miningof sylvinite or carnallite to obtain potassium chloride, a valuablemineral having use, inter alia, as an agricultural nutrient. By usingthe tachydrite solution it is possible to precipitate carnallite orsylvinite quickly from their so lutions without the use of heat. Thecarnallite or sylvinite may then be processed for the recovery ofpotassium values by conventional techniques.

The solution mining of ores employs well known techniques and will notbe described in great detail here. In one solution mining technique, twoor more pipes are sunk into the desired ore body. Water or a brine,unsaturated with respect to the mineral to be dissolved, is pumped intothe ore body through one or more pipes and exits from the ore bodythrough one or more other pipes, to provide a continuous flow of liquidthrough the ore. In another solution mining technique, concentric pipesare employed with fluid being pumped into ore body through one pipe andremoved from the ore body through the other. While solution mining ismost frequently conducted as a continuous operation, it can be conductedas a batch operation in which fluid is pumped into the ore body andpermitted to remain there for a period of time before being removed.

In deposits such as the Sergipe, the carnallite and tachydrite can beexpected to undergo plastic deformation because of strain as some of themineral values are removed. During solution mining of a body such as theSergipe, the plastic deformation will tend to move the ore toward theliquid inlet thereby making the ore more readily available. Thepotential plastic deformation may also provide an artesian effect.Liquid may be pumped into the ore body which, upon plastic deformation,will exert sufficient pressure to cause the liquid to flow back towardthe surface when the valve on the exit line is opened. This inventioncontemplates forming solutions underground at pressures normallyencountered as well as at induced higher pressures.

The solutions employed in the practice of this inven tion aresubstantially saturated solutions with respect to the mineral to berecovered. While substantially complete saturation is desirable, theterm saturated solution as used herein includes solutions that are atleast about 80% saturated with those that are at least about 90%saturated being more desirable. The term saturated re fers to themaximum amount of the desired mineral a given solution can dissolve atthe temperature of the reaction between the mineral solution and thetachydrite solution. By way of example, at 50C a saturated solution ofcarnallite ore will contain about 7.6 mols of KCl, 3.8 mols of NaCl and77 mols of MgCl whereas a saturated solution of sylvinite at 50C willcontain about 27 mols of KCl and 44 mols of NaCl. A 35C solution oftachydrite will contain about 26.5% CaCl about l8.5% MgCl and about 0.3%NaCl.

Generally, the temperatures at which the solutions are mixed will bethose that result naturally in the process i.e., those of the mineralformation modified by the various heats of solution. It should berecognized that since the heat of solution of tachydrite is exothermicwhereas the heat of solution of other minerals may be endothermic, thetemperatures of the solutions coming from the ground may vary somewhat.Generally, the temperature of mixing will be within the range of fromabout 20C to about 60C. The mineral solution:tachydrite solution weightratio will often be about lzl but may vary more broadly with ratios offrom about l:O.5 to about 1:l.5 generally being used. The temperaturefor the mixing, the degree of saturation of the solutions, and the ratioof the ingredients as well as other aspects of the mixing are within theskill of the art.

The practice of this invention may more readily be understood byreference to the accompanying FIGS. 1-2 which depict typical embodimentsof this invention.

FIG. 1 depicts a schematic flowsheet for the processing of carnalliteore. Water or a brine is pumped into a carnallite ore zone through line1 and exits from the ore zone through line 2 as a substantiallysaturated solution of carnallite ore. A brine containing calciumchloride and magnesium chloride, or water, is introduced into atachydrite ore zone through line 3 and exits through line 4 as asubstantially saturated solution of tachydrite ore. If desired, eachstream may be conducted to holding pits wherein clay or gangue may bepermitted to settle out. The streams are mixed in reaction tanks 5 toform a slurry of camallite in brine. The slurry is conducted throughline 6 to thickener 7 and the overflow from the thickener, a brinecontaining calcium chloride and magnesium chloride, is removed from theprocess through line 8. This stream may, if desired, be used as a sourceof bromine or other trace constituents which may be recovered byconventional techniques.

A portion of brine stream from line 8, if desired, may be employed as abrine to be conducted into the tachydrite ore body through line 3.inasmuch as carnallite was precipitated in reaction tanks 5, the brinestream leaving the process through line 8 is no longer saturated and,therefore, is capable of dissolving additional tachydrite ore. Since theheat of solution of calcium chloride is exothermic, the brine will tendto be heated in the tachydrite ore zone thereby aiding in the rapidsolution of the tachydrite ore.

The thickened slurry from thickener 7 exits through line 9 and may, isdesired, be conducted to filter 10 where it is washed with water orother solution entering through line ll. Optionally, the filtrate fromfilter 10 may be recycled to the thickener 7 through line 12.

The washed cake from filter 10 may be subject to beneficiation byconventional means to produce potassium chloride, and a magnesiumchloride stream. In one conventional beneficiation, the solids areconducted through line 13 to decomposition tank 14 wherein they arecombined with water added through line 15. Limited amounts of water areadded at ambient temperatures to decompose the carnallite and providepotassium chloride solids and a magnesium chloride solution.Decomposition of carnallite with water is known in the art and providesa slurry predominately containing sylvite but which also may containminor amounts of halite. The slurry is conducted through line 16 tothickener 17 to provide an overflow stream 18 which contains substantialamounts of magnesium chloride and sodium chloride. This stream may, ifdesired, be processed by conventional means to provide magnesiumchloride product.

The thickened slurry from thickener I7 is conducted to filter 20 throughline 19. The filter cake is washed with water introduced through line 2!and the filtrate may be recycled through line 22 to thickener l7.Following the wash, the product is removed through line 23 to drier 24where it is dried to provide a potassium chloride product that exits at25 and which may have a grade of 62% K 0.

FIG. 2 is a schematic flow sheet for the processing of sylvinite ore.Water or brine is pumped into the sylvinite ore zone through line 51 andexits from the ore zone through line 52 as a substantially saturatedsolution. A brine containing calcium chloride and magnesium chloride, orwater, is introduced into the tachydrite zone through line 53 and exitsfrom the ore zone through line 54 as a substantially saturated solutionof tachydrite ore. The solutions are combined in reaction tanks 55 toform a slurry of sylvinite in brine. The slurry is conducted throughline 56 to thickener 57 and the overflow from the thickener, a brinecontaining calcium chloride and magnesium chloride is removed from theprocess through line 58. This stream is a source of bromine and othertrace constituents. A portion of the brine stream may, if desired, berecycled into the tachydrite ore body through line 53. Since the bleedstream is no longer saturated with regard to tachydrite, it is capableof dissolving additional ore.

The sylvinite from thickener 57 optionally may be conducted through line59 to filter 60 where it is washed with water or brine (such as onesaturated with respect to potassium chloride) introduced through line61. The filtrate may be returned through line 62 to thickener 57. Themixture of potassium chloride and sodium chloride solids is conductedthrough line 63 to a beneficiation 64. The mixture of potassium chlorideand sodium chloride may be beneficiated to provide potassium chlorideand sodium chloride by a variety of beneficiation techniques which arewell known in the art. For example, the mixture may be treated with aflo tation agent and subjected to floth flotation, the mixture may besubjected to differential crystalization, the

mixture may be selectively leached, or the like. The specifics of thesetechniques are well known and readily available to the art. in FIG. 2,potassium chloride product exits from the process through line 65 whilehalite exits through line 66.

While FIG. 1 depicts the processing of the carnallite ore and FIG. 2depicts the processing of sylvinite ore, this invention is alsoapplicable to solutions formed from mixtures of sylvinite and carnallitewhich may be encountered in mixed ore deposits such as the Sergipedeposit. Such deposit is substantially free of sulfate and readily maybe processed according to this invention.

in a third embodiment of this invention, a solution saturated withrespect to halite is mixed with a solution saturated with respect totachydrite ore to provide solid sodium chloride. The slurry of sodiumchloride may be processed through a thickener and thereafter filteredand washed in a manner comparable to the processing shown in FIGS. 1 and2. It should be understood that the saturated halite solution may beformed by solution mining or may be formed as a process stream in thebeneficiation of sylvinite.

The following examples are included in order to more fully illustratethe practice of this invention. These examples are included forillustrative purposes only and in no way are intended to limit the scopeof this invention.

EXAMPLE 1 One part of a substantially concentrated solution ofcarnallite was mixed with one part of a substantially concentratedsolution of tachydrite at a temperature of 50C. Solids were formed thatcontained magnesium chloride and potassium chloride. The solid analyzed11.48% potassium, 8.48% magnesium, l.2% calcium and 35.58% chlorine.This mixture is suitable for processing according to the process of FIG.1 to produce a potassium chloride product.

EXAMPLE 2 One part of a saturated solution of sylvinite was formed andmixed with one part of a saturated solution of tachydrite at 50C. Thesolids that formed contained potassium chloride and sodium chloride.They were analyzed and contained 18.] l% potassium, 0.68% magnesium,l.26% calcium, l9.40% sodium, and 50.6l% chlorine. This mixture issuitable for processing according to the process of FIG. 2 to provide apotassium chloride product.

EXAMPLE 3 One part of a solution saturated with carnallite ore,

one part of a solution saturated with respect to sylvinite ore and onepart of a solution saturated with respect to tachydrite ore were mixedat 50C and solids were permitted to form. The solids analyzed l5.02%potassium, l.37% magnesium. 0.78% calcium, I9. I 6% sodium and 48.6%chlorine. This mixture is suitable for processing to provide potassiumchloride product.

EXAMPLE 4 One part of a solution saturated with halite was mixed withone part of a saturated solution of tachydrite at 50C. The solids thatformed were analyzed and contained'32.02% sodium, 53.94% chlorine, 0.55%potassium, 0.65% magnesium and l.2% calcium.

Since modification of this invention will be apparent to those skilledin the art, it is intended that this invention be limited only by thescope of the appended claims.

I claim:

1. A process which comprises:

1. forming a saturated aqueous solution of tachydrite ore;

2. forming an aqueous solution containing carnallite. sylvinite ormixtures thereof, saturated with respect to potassium chloride;

3. mixing said solutions in a mineral solution: tachydrite solutionweight ratio of from about l:0.5 to about l:l.5 and at a temperature offrom about 20C to about C whereby potassium chloridecontaining solidsare precipitated; and

4. beneficiating said potassium chloride-containing solids to providepotassium chloride.

2. The process of claim 1 wherein said second saturated aqueous solutionis a solution of carnallitc.

3. The process of claim I wherein said second saturated solution is asolution of sylvinite.

4. The process of claim I wherein said second saturation aqueoussolution is a solution of a mixture of carnallite and sylvinite.

5. The process of claim 1 wherein said second aqueous solution is asolution containing carnallite and wherein said precipitated solidswhich contain carnallite are beneficiated by contacting them with waterto form a solution containing magnesium chloride and provide a potassiumchloride solids product.

6. The process of claim I wherein said second aqueous solution is asolution containing sylvinite and said precipitated potassiumchloride-containing solids are subjected to froth flotation to provide apotassium chloride product.

i i 4' l l

1. A PROCESS WHICH COMPRISES:
 1. FRMING A STURATED AQUEOUS SOLUTION OFTACHYDRITE ORE,
 2. FORMING AN AQUEOUS SOLUTION CONTAINING CARNALLITE,SYLVINITE OR MIXTURES THEREOF, SATURATED WITH RESPECT TO POTASSIUMCHLORIDE.
 2. The process of claim 1 wherein said second saturatedaqueous solution is a solution of carnallite.
 2. forming an aqueoussolution containing carnallite, sylvinite or mixtures thereof, saturatedwith respect to potassium chloride;
 3. mixing said solutions in amineral solution: tachydrite solution weight ratio of from about 1:0.5to about 1:1.5 and at a temperature of from about 20*C to about 60*Cwhereby potassium chloride-containing solids are precipitated; and 3.The process of claim 1 wherein said second saturated solution is asolution of sylvinite.
 3. MIXING SAID OLUTIONS IN A MINERAL SOLUTION:TACHYDRITE SOLUTION WEIGHT RATIO OF FROM ABOUT 1:0.5 TO ABOUT 1:1.5 ANDAT A TEMPERATURE OF FROM ABOUT 20*C TO ABOUT 60*C WHEREBY POSTASSIUMCHLORIDE-CONTAINING SOLIDS ARE PREDIPUTATED AND
 4. BENEFICIATING SAIDPOSTASSIUM CHLORIDE-CONTAINING SOLIDS TO PROVIDE POTASSIUM CHLORIDE. 4.The process of claim 1 wherein said second saturation aqueous solutionis a solution of a mixture of carnallite and sylvinite.
 4. beneficiatingsaid potassium chloride-containing solids to provide potassium chloride.5. The process of claim 1 wherein said second aqueous solution is asolution containing carnallite and wherein said precipitated solidswhich contain carnallite are beneficiated by contacting them with waterto form a solution containing magnesium chloride and provide a potassiumchloride solids product.
 6. The process of claim 1 wherein said secondaqueous solution is a solution containing sylvinite and saidprecipitated potassium chloride-containing solids are subjected to frothflotation to provide a potassium chloride product.